paracetamol sample preparations

[ydna6969]

Hi
Anybody having assay problems with paracetamol tablets.
We get variability which results in repeat work with no clear root cause of problem.
We are going to introduce mechanical shaking to avoid manual shaking introducing variability.
Does anyone test paracetamol regularly using an HPLC method and if so ever had any issues and any tips on how to ensure suitable homogenised solutions?

Thanks

[DR]

Solubility is not a major problem but it does take some time. Also, a secondary dilution is usually called for due to the very high extinction coefficient - if you are not careful, you can get mesas (flat topped peaks below full scale of the detector) instead of peaks!

[ydna6969]

Hi ,

Thanks for your reply.
We carry out a second dilution for this sample preparation.
Still no root cause to out of spec results.

Any further ideas let me know

[bunnahabhain]

Is your initial step a suspension or clear solution? If suspension, try to sonicate for better homogenisation. Be sure to youse a rather large volume for the next dilution step, maybe cut the pipette tips to avoid clogging or reduced flow through the narrow holes. Or, use a bigger initial volume to dissolve/suspend your tablets in.